Timing chain tensioner repair?

They only replaced the tensioner. I have seen a number of videos that say you should use a timing chain kit if the tensioner needs replacing. The car is currently at the dealership. Told me it would cost over $15,000 to repair (rod bearings?). This happened after two weeks of driving after they replaced the timing chain tensioner.

When I picked the vehicle up from the dealership the timing chain rattled as before - when I started it there! But it was just before closing and we were leaving the next morning to visit my son. Vehicle drove fine except for the timing chain rattling against the housing about 60% of the time I started it.

Thank you for responding. The dealership won’t honor their service warranty (12 months or 12,000 miles). They won’t refund any of the $4300 I paid to have it repaired. Also told me lies about the vehicle being 5 quarts low on oil (I literally checked it right before I took it in), I was 2000 miles past recommended oil change time (I showed them proof that next oil change was due in another 1500 miles), and that I didn’t put in the oil recommended by Kia (10w-30 synthetic - which was the same oil listed on my receipt from my last oil change).

Now they are telling me that the rod problem I have now has nothing to do with the timing chain tensioner. I’ve been doing research and that has told me that if timing chain issue is ignored it can lead to damage to the rods.